Hey all:
Have any of you come across an example of persisting a ContentCache to disk and
reading it back on app launch? We have lots of icons and logos for hundreds of
companies and they don't change between sessions.
Like this (doesn't work though). ImageCache is a subclass of ContentCache to
get access to the protected cachedData:Dictionary which is key/value pairs,
with key as URL to image, and value is bitmapData.
public function saveImageCache(imageCache:ImageCache):void {
var cacheFile:File = File.applicationStorageDirectory;
cacheFile = cacheFile.resolvePath(IMAGE_CACHE_FILE_NAME);
if (cacheFile.exists) {
cacheFile.deleteFile();
}
var fileStream:FileStream = new FileStream();
fileStream.open(cacheFile, FileMode.WRITE);
fileStream.writeObject(imageCache.getEntries()); // this is a Dictionary
with byte array for image as value
fileStream.close();
}
The writeObject API of FileStream does not marshal the bitmapData to disk.
/**
* Loads a persisted image cache from disk.
*
* @return ContentCache
*/
public function loadImageCache():ImageCache {
var cacheFile:File = File.applicationStorageDirectory;
cacheFile = cacheFile.resolvePath(IMAGE_CACHE_FILE_NAME);
if (cacheFile.exists) {
var fileStream:FileStream = new FileStream();
fileStream.open(cacheFile, FileMode.READ);
var entries:Dictionary = fileStream.readObject() as Dictionary;
fileStream.close();
var imageCache:ImageCache = new ImageCache();
imageCache.loadEntries(entries);
return imageCache;
}
return null;
}
The entries variable does populate with all the keys as URLs, but the values
are null. FileStream won't read just raw binary data in this way.
I don't want to have to save every image using an encoder into separate files
and then load them all back if I can help it.
Just seems FileStream should be able to just write a blob of binary data to
disk and retrieve it "as-is" but it doesn't or I can't find the way.
Thanks for your suggestions.
Erik
